---
_id: '22057'
abstract:
- lang: eng
  text: "We construct more efficient cryptosystems with provable\r\nsecurity against
    adaptive attacks, based on simple and natural hardness\r\nassumptions in the standard
    model. Concretely, we describe:\r\n– An adaptively-secure variant of the efficient,
    selectively-secure LWE-\r\nbased identity-based encryption (IBE) scheme of Agrawal,
    Boneh,\r\nand Boyen (EUROCRYPT 2010). In comparison to the previously\r\nmost
    efficient such scheme by Yamada (CRYPTO 2017) we achieve\r\nsmaller lattice parameters
    and shorter public keys of size O(log λ),\r\nwhere λ is the security parameter.\r\n–
    Adaptively-secure variants of two efficient selectively-secure pairing-\r\nbased
    IBEs of Boneh and Boyen (EUROCRYPT 2004). One is based\r\non the DBDH assumption,
    has the same ciphertext size as the cor-\r\nresponding BB04 scheme, and achieves
    full adaptive security with\r\npublic parameters of size only O(log λ). The other
    is based on a q-\r\ntype assumption and has public key size O(λ), but a ciphertext
    is\r\nonly a single group element and the security reduction is quadrat-\r\nically
    tighter than the corresponding scheme by Jager and Kurek\r\n(ASIACRYPT 2018).\r\n–
    A very efficient adaptively-secure verifiable random function where\r\nproofs,
    public keys, and secret keys have size O(log λ).\r\nAs a technical contribution
    we introduce blockwise partitioning, which\r\nleverages the assumption that a
    cryptographic hash function is weak\r\nnear-collision resistant to prove full
    adaptive security of cryptosystems."
author:
- first_name: Tibor
  full_name: Jager, Tibor
  last_name: Jager
- first_name: Rafael
  full_name: Kurek, Rafael
  last_name: Kurek
- first_name: David
  full_name: Niehues, David
  id: '36113'
  last_name: Niehues
citation:
  ama: 'Jager T, Kurek R, Niehues D. Efficient Adaptively-Secure IB-KEMs and VRFs
    via Near-Collision Resistance. In: <i>Public-Key Cryptography – PKC 2021</i>.
    Cham; 2021. doi:<a href="https://doi.org/10.1007/978-3-030-75245-3_22">10.1007/978-3-030-75245-3_22</a>'
  apa: Jager, T., Kurek, R., &#38; Niehues, D. (2021). Efficient Adaptively-Secure
    IB-KEMs and VRFs via Near-Collision Resistance. In <i>Public-Key Cryptography
    – PKC 2021</i>. Cham. <a href="https://doi.org/10.1007/978-3-030-75245-3_22">https://doi.org/10.1007/978-3-030-75245-3_22</a>
  bibtex: '@inbook{Jager_Kurek_Niehues_2021, place={Cham}, title={Efficient Adaptively-Secure
    IB-KEMs and VRFs via Near-Collision Resistance}, DOI={<a href="https://doi.org/10.1007/978-3-030-75245-3_22">10.1007/978-3-030-75245-3_22</a>},
    booktitle={Public-Key Cryptography – PKC 2021}, author={Jager, Tibor and Kurek,
    Rafael and Niehues, David}, year={2021} }'
  chicago: Jager, Tibor, Rafael Kurek, and David Niehues. “Efficient Adaptively-Secure
    IB-KEMs and VRFs via Near-Collision Resistance.” In <i>Public-Key Cryptography
    – PKC 2021</i>. Cham, 2021. <a href="https://doi.org/10.1007/978-3-030-75245-3_22">https://doi.org/10.1007/978-3-030-75245-3_22</a>.
  ieee: T. Jager, R. Kurek, and D. Niehues, “Efficient Adaptively-Secure IB-KEMs and
    VRFs via Near-Collision Resistance,” in <i>Public-Key Cryptography – PKC 2021</i>,
    Cham, 2021.
  mla: Jager, Tibor, et al. “Efficient Adaptively-Secure IB-KEMs and VRFs via Near-Collision
    Resistance.” <i>Public-Key Cryptography – PKC 2021</i>, 2021, doi:<a href="https://doi.org/10.1007/978-3-030-75245-3_22">10.1007/978-3-030-75245-3_22</a>.
  short: 'T. Jager, R. Kurek, D. Niehues, in: Public-Key Cryptography – PKC 2021,
    Cham, 2021.'
date_created: 2021-05-10T15:56:24Z
date_updated: 2022-01-06T06:55:23Z
ddc:
- '000'
department:
- _id: '558'
doi: 10.1007/978-3-030-75245-3_22
file:
- access_level: closed
  content_type: application/pdf
  creator: davnie
  date_created: 2021-05-10T16:02:02Z
  date_updated: 2021-05-10T16:02:02Z
  file_id: '22058'
  file_name: Jager et al. - 2021 - Efficient Adaptively-Secure IB-KEMs and VRFs via
    N.pdf
  file_size: 701068
  relation: main_file
file_date_updated: 2021-05-10T16:02:02Z
has_accepted_license: '1'
language:
- iso: eng
place: Cham
project:
- _id: '1'
  name: SFB 901
- _id: '4'
  name: SFB 901 - Project Area C
- _id: '13'
  name: SFB 901 - Subproject C1
publication: Public-Key Cryptography – PKC 2021
publication_identifier:
  isbn:
  - '9783030752446'
  - '9783030752453'
  issn:
  - 0302-9743
  - 1611-3349
publication_status: published
status: public
title: Efficient Adaptively-Secure IB-KEMs and VRFs via Near-Collision Resistance
type: book_chapter
user_id: '36113'
year: '2021'
...